Bifidobacterium longum IPLA20022 is able to counteract the cytotoxic effect of clostridium difficile upon HT29 colonocytes

Abstract

[Backgrounds] Infections caused by Clostridium difficile are increasing and constitute a problem due to the high morbidity and mortality rates in groups of risk, being the main aetiological agent of antibiotic-associated diarrhoea. This opportunistic pathogen is a common inhabitant of the intestinal microbiota but starts to proliferate after a microbiota dysbiosis caused by antibiotic treatment. The major virulence factor is the production of different toxins, mainly A and B. In previous works we have selected the strain Bifidobacterium longum IPLA20022 as a probiotic candidate being able to in vitro reduce the toxicity of C. difficile LMG21717 producing both types of toxins. [Objectives] Our aim is to gain insight into the potential mechanisms involved in the ability of IPLA20022 strain to reduce the cytotoxic effect of C. difficile upon an intestinal epithelial monolayer obtained from HT29 cells. [Methods] Different cellular fractions were obtained from B. longum IPLA20022 and were incubated with C. difficile. Afterwards, the cell-free supernatants were tested for their anti-clostridial capability upon HT29 cells using the RTCA (real time cell analyser) technology following the integrity of the intestinal monolayer; the remaining toxins were analyzed by means of ELISA tests. Those bifidobacterial fractions showing capability to reduce the toxicity of C. difficile were analyzed by means of proteomic techniques. [Conclusions] Preliminary results show that extracellular factors from B. longum IPLA20022 are involved in the reduction of clostridial cytotoxicity. This opens new opportunities for the therapeutically application of the strain, or their metabolites, for attenuating symptoms of C. difficile infection